QuestionQUESTION: This is regarding the hot air hose that is connected to the air intake filter to the carburetor. The hose terminates at the exhaust manifold where it picks up the hot air. There is no evidence that it could be attached to the exhaust manifold. I would like to know if this is by design or is some kind of connection to the exhaust manifold missing? My Best Regards.
ANSWER: I can't remember what these Spitfire-engined Midgets had as an arrangement for this hose. Normally there would be a small "stove" riveted to the manifold with a short cylindrical spout over which the hose would fit. Given that these cars had to be "smogified" to sell in the U.S., this part may have been clamped on or even crimped in place. And, it very well may have fallen off. Do you need it? In a word, no. By providing preheated air to the carburetor, it ensures that the fuel dispensed by the carburetor is more thoroughly atomized in the intake air stream and therefore more completely (cleanly) burned. There should be a thermostatically operated flap or valve in the air cleaner inlet that shuts off the air coming from this hose once the engine warms up. As a rule, this hotter air during warm-up does not affect the way the engine operates; but, it is important that this hot air does not reach the engine when it is at normal operating temperature. You need the coldest, densest air you can get then. So, more importantly than seeing if it works, make sure it is not working when the engine warms up.
---------- FOLLOW-UP ----------
QUESTION: Thanks Mike for your very descriptive answer. Hopefully the smog control examiner will take this under advisement when reevaluating my car. To follow up, would you have information or suggest where I might acquire a schematic sketch of the stove connection to the manifold. My shop manual show the top connection only.Thanks again.
Answer As long as you are committed to owning a thirty-plus year old English car, you will need the resources of Moss Motors. Their website is http://www.mossmotors.com and they will have any and all parts that you need. They probably can sell you that little gizmo for your exhaust manifold. If they don't show it on their website, give them a call, they're always very helpful. Worst case is that you can't find one anywhere, and you have to buy a universal one. If one of the bigger parts stores doesn't have it, then look on J.C. Whitney's website, I'm sure that they carry a universal clamp-on kit.
